1. Field of the Invention
The present invention relates to an electronic still camera, and in particular, to an electronic still camera in which video signals representative of a still image developed from a solid-state imaging device are recorded on a rotary recording medium such as a magnetic disk.
2. Description of the Prior Art
Unique to a solid-state imaging device is the problem of a noise mixed in the video signals due to a dark current caused by a thermal excitation of carriers in a device structure. When shooting a moving image, video signals are successively produced from a solid-state imaging device, and hence the noise caused by the dark current is not so remarkable. However, when compared with the moving picture, a quite higher clarity or distinctness is required for a still picture; furthermore, when shooting a still picture, video signals are read out from the imaging device only after the shutter is opened to expose the solid-state imaging device to a light incident from an object. Consequently, there exists a higher possibility for carriers caused by the dark current to be accumulated in the device structure, which requires a careful removal of the noise component due to the dark current to reproduce a picture with a high quality.
To solve the problem, according to the Japanese Patent Laid-Open Publication No. 105775/1984, there has been disclosed an electronic still camera in which a trailing edge of a shutter open signal for opening a shutter to expose a solid-state image device is controlled to be substantially overlapped with a leading edge of a recording gate signal for recording video signals from the solid-state imaging device onto a recording medium. However, for a mechanism of a mechanical shutter, there exists a quite long time delay from when a shutter open signal is energized to when a plane of the shutter is actually opened and closed. Consequently, in a camera using such a shutter mechanism, even if the trailing edge of the shutter open signal is controlled to be substantially overlapped with the leading edge of the recording gate signal, a dark current which cannot be ignored may flow during the delay time in some cases.